Dentifrice is typically made in vacuum vessels using some type of high energy mixing device, to combine the various components. The liquids are usually added to the vacuum vessel as a first step. Flavor or other oils can be added at various points within the batch during the mixing process to minimize loss and maximize within batch antifoaming benefits. The salts are added either directly to the mix tank or added to a slurry tank first then added to the mix tank. The abrasive is typically added directly to the mix tank, however it is possible the abrasive could be pre slurried and delivered to the mix tank as a premix.
Rheology modifiers are either added directly to the mix tank or added via offline pre slurry (tank or inline). The direct to the tank option requires significant within batch mixing (typically high energy) which can take significant processing time to complete. The offline option requires more capital assets to support the different formulations. Typically the final step of currently used processes is the addition of the surfactant. Keeping the surfactant to the end of the batch makes tank deaeration easier to complete. Even with holding the surfactant to the end of the process, when making the dentifrice batch on the residual of the previous batch, the residual surfactant from the first batch can cause significant challenges on deaeration. These challenges can account for up to 30% of the total process time in making toothpaste.
The ingredients are typically combined together in the mix tank by recirculating the ingredients through a high shear mixing device to create a final homogenous product composition. Vacuum is then applied to the mix tank to deaerate the dentifrice to the desired finished density. The addition of rheology modifiers thickens the premix making dearation more difficult, as it is harder to pull air out of a thick premix. Due to the addition of the rheology modifiers during the mixing process the premix has a paste like viscosity that clings to the internal mix tank surfaces, preventing the complete removal of the premix when it is pumped out of the mix tank. This requires the mix tank to be cleaned prior to making another product formula. It currently takes substantial length of time (>1 hr) and large amounts of water to clean a mix tank. This results in a greatly reduced making capacity due to lost time, as new formulas cannot be made while the system is being cleaned. Therefore due to the high viscosity of the finished product, processing time is slow and losses are high.
What is needed is a personal care composition making methodology that has reduced down-time due to inter batch cleaning times.